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Mercury (Hg) inMercury (Hg) inMercury (Hg) in Mercury (Hg) in OxyOxy--Coal Fired Power Plant with COCoal Fired Power Plant with CO22 CaptureCapture
What is the Real Score???What is the Real Score???What is the Real Score???What is the Real Score???
by
Stanley SantosIEA Greenhouse Gas R&D Programme
Cheltenham, UK
http://www.ieagreen.org.uk*Corresponding Author’s Email: stanley@ieaghg.org
AcknowledgementsAcknowledgements• Lesley Sloss (IEA Clean Coal Centre)
J t W dt (Ut h U i it )• Jost Wendt (Utah University)• Vince White (Air Products)• Minish Shah, Sho Kobayashi (Praxair)• Denis Cieutat Jean Pierre Tranier (Air Liquide)• Denis Cieutat, Jean Pierre Tranier (Air Liquide)• Rodney Allam• …
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Objectives of this PresentationObjectives of this Presentationjj• To provide awareness the impact / risk of ignoring
Hg in any Oxy-Coal Combustion Power Plant withHg in any Oxy Coal Combustion Power Plant with CO2 Capture
• To initiate discussion on the issue of Mercury in• To initiate discussion on the issue of Mercury in Oxy-Coal Combustion Power Plant
• To initiate a review on the different factors to reconsider on the design of coal power plant in the perspective of Hg.
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CO2 Compression and Purification System –Inerts removal and compression to 110 bar
Flue Gas Expander
Aluminium plate/fin exchangerFlue GasHeater
Flue Gas Vent
1 1 bar Expander1.1 bar20°C
25% CO275% 55°C75% inerts
-55°C
Driers
CO2 product110 bar
96% CO
30 bar Raw CO
96% CO24% Inerts-60°C dp
4
30 bar Raw CO2Saturated 30°C
76% CO2 24% Inerts
Case Study:Case Study:
M b G P i Pl t Fi I id tM b G P i Pl t Fi I id tMoomba Gas Processing Plant Fire IncidentMoomba Gas Processing Plant Fire Incident(01 January 2004)(01 January 2004)
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Safety Incident• Moomba Gas Processing Plant owned by Santos is the main
supplier of natural gas to South Australia and New Southsupplier of natural gas to South Australia and New South Wales○ Liquids separated from raw natural gas via 2 trains of LRP (Liquids q p g ( q
Recovery Plant)○ Liquids (condensate and LPG) sent to Port Bonython for export (about
650Km south of Moomba)650Km south of Moomba)
• About 02.43 in the morning, 1st January 2004 – an explosion & fire occurred at Train A of the LRP section& fire occurred at Train A of the LRP section.○ The fire incident also damaged Train B.
• Effect: liquids production interrupted for 8 months
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• Effect: liquids production interrupted for 8 months
Failure Location
• Failure occurred at the base (6 o’clock) of the gas nozzle• Evidence of de-lamination consistent with Liquid Metal Embrittlement
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q(LME) caused by mercury in contact with aluminium
Other potential failure caused by HgFurther inspection of the cold box after the incident showedbox after the incident showed evidence of pitting to the aluminium surface in several parts of the heat exchanger.
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This is How Mercury attacksThis is How Mercury attacks the Aluminium
Figure 1: A small amount of mercury attacking an aluminium beam in less than an hour
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[courtesy of Popular Science website].
Understanding Failure Mechanisms• Failure Mechanisms
○ Amalgamation○ Amalgam Corrosion○ Amalgam Corrosion○ Liquid metal embrittlement○ Galvanic Corrosion
• Factors that could increase the probability of failure are:○ Hg accumulation (i e due to shut down and process upsets)○ Hg accumulation (i.e. due to shut down and process upsets)○ In addition to the presence of mechanical and thermal stress, and○ moisture
• Accumulation would not occur under normal operating condition (i e -40oC and below)
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condition (i.e. 40 C and below)
Understanding Failure MechanismsUnderstanding Failure Mechanisms
• Statement from ALPEMA:• Statement from ALPEMA: In general, mercury will not react with aluminium unless it is allowed to exist in contact with the heat exchanger in its li id t t d th i t t If th ditiliquid state and there is water present. If these conditions exist within a heat exchanger, then mercury contamination can result in problems. This attack is most severe when pcoupled with another corrosion process.
• QUESTION #1: How dry do we need to go?
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Understanding Failure Mechanisms
• Known failures of BAHX due to mercury attack (i.e. Algeria, y ( g ,Thailand, Australia) are random events!!!
• Statement from UOP Background Paper:Since the level of mercury that can be tolerated is not established, most operators want to remove it “all ” That is remove it to a level where itoperators want to remove it all. That is, remove it to a level where it can not be detected with the available analytical capability. Currently, this means reducing the mercury to less than 0.01 μg/Nm3.
• QUESTION #2: Is the 0.01 μg/Nm3 to be used as well in the oxy coal combustion power plant?
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well in the oxy-coal combustion power plant?
What are the Concerns???What are the Concerns???• Mercury from LNG plant are mostly elemental Hg
and some organo Hg speciesand some organo-Hg species.○ There are no technical barrier in removing mercury. This
is achieved by using Activated Carbon Bed or otheris achieved by using Activated Carbon Bed or other adsorbent.
I C l Fi d C H ill i th f f• In Coal Fired Case, Hg will come in the form of elemental Hg (as particulates or vapour) or Hg2+
( tl i th f f H Cl )(mostly in the form of HgCl2)• QUESTION #3: What is the speciation of Hg in an
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oxy-coal combustion cases?17
Conversion of Hg to HgConversion of Hg to Hg2+2+
• Clearly established in Air Fired Cases that the benefits of co removal of Hg with FGD and SCRbenefits of co-removal of Hg with FGD and SCR are due to conversion of Hg (elemental) to Hg2+
• Correlation with Cl content of the coal is well established – this promote conversion to Hg2+
• Question #5: What will be the rate of conversion from Hg to Hg2+ in oxy-combustion case?g g y
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Impact of SOImpact of SO33
Data from ANL Studies (1980s)Data from ANL Studies (1980s) Black Thunder CoalBlack Thunder CoalData from ANL Studies (1980s) Data from ANL Studies (1980s) -- Black Thunder CoalBlack Thunder Coal
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U i ität St tt t
Measured SO3 concentrations for Lausitz coalat AIR and OXYFUEL combustion conditions Universität Stuttgart
SO3 measured,ppm
at AIR and OXYFUEL combustion conditions
120
140
ppm
OXYFUELSO2 SO3
80
100
120 measured measured
ppm ppm
60
80AIR 733 8 (6 – 11)*
OXYFUEL 1758 85 (36 – 121)*
20
40AIR
00 500 1000 1500 2000 2500
SO t t itiSO2 at measurment position, ppm* ... min. / max. value measured
Impact of SO3 on Hg Removal Efficiencyg yAir Fired Case (CODEN Study) Oxy Fired Case
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Mercury Management in the CO2 Processing Plant
• No technical barrier in removing Hg. This has been done in LNG industry The consideration of cost isdone in LNG industry. The consideration of cost is the main question!
• There are 3 levels where Hg (both elemental and ionic) could be captured in the CO processingionic) could be captured in the CO2 processing plant.
Compression stage○ Compression stage○ Moisture Removal stage
Activated Carbon Guard bed
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○ Activated Carbon Guard bed
CO2 Compression and Purification System –2Removal of SO2, NOx and Hg
SO2 removal: 100% NOx removal: 90-99%1.02 bar
30°C67% CO28% H2O
30 bar to DriersSaturated 30°C
76% CO28% H2O25% InertsSOx
224% Inerts
BFW15 bar
Water
NOx BFW
Condensate
30 barcw
cw
cw
Dilute H2SO4
Dilute HNO3
24
2 4 HNO3
Hg
NG Industry Practice (Data from Calgon 1996)(Data from Calgon 1996)
• Activated Carbon bed is generally employed This isgenerally employed. This is expected to be applied to oxy-combustion oxy-PC as y ywell.
• It is important to be aware with regard to short term performance drop of the activated carbon bed during h t d t
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shut down or process upset.
Mercury Sorbent Technologies (From M. Wilhelm, 1995 – Mercury Technology Services)( , y gy )
Q ti 7 Wh t ibl i t fQuestion 7: What are possible impact of NOx and Oxygen to these substrates?
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Hg Cleaning Process Environmental ConsiderationEnvironmental Consideration
• It should be expected that future environmental regulation would require recovery of Hg and back torecovery of Hg and back to the commercial cycle!
• Question #8: Can we recover Hg from therecover Hg from the wastewater sludges, ash bin and other sink etc...
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bin and other sink etc...(M. Wilhelm, 1995)
Mercury Analysis Method(From M. Wilhelm, 1995 – Mercury Technology Services)(From M. Wilhelm, 1995 Mercury Technology Services)
• Colorimetric 2000 ng• X Ray Flourescence 10 ng• X-Ray Flourescence 10 ng• Neutron Activation 2 ng
G ld Fil 0 5• Gold Film 0.5 ng• Differential Pulse Voltametry 0.04 ng• Cold Vapor Atomic Absorption 0.01 ng• Cold Vapor Atomic Flourescence 0.0001 ng
Question #9: Can we really measure mercury at the
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very low level?
The Real Score…The Real Score…
• What is the real issue?○ The real issue is how much Hg we are
delivering to the CO2 processing unitg p g○ What type of Hg species we are introducing
to the CO2 processing unit?to the CO2 processing unit?○ What is the most cost effective way of Hg
l t b i l d d i thremoval process to be included in the power plant?
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